U.S. patent application number 10/759692 was filed with the patent office on 2004-08-05 for oxygen-enriched niobium wire.
This patent application is currently assigned to W. C. Heraeus GmbH & Co. KG. Invention is credited to Spaniol, Bernd.
Application Number | 20040149356 10/759692 |
Document ID | / |
Family ID | 32747579 |
Filed Date | 2004-08-05 |
United States Patent
Application |
20040149356 |
Kind Code |
A1 |
Spaniol, Bernd |
August 5, 2004 |
Oxygen-enriched niobium wire
Abstract
A niobium wire, a process for producing it, and its use for
connection to niobium or niobium oxide capacitors. The wire is
enriched with oxygen and preferably has oxygen concentrations of
about 3,000 to 30,000 .mu.g/g.
Inventors: |
Spaniol, Bernd;
(Hammersbach, DE) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
W. C. Heraeus GmbH & Co.
KG
|
Family ID: |
32747579 |
Appl. No.: |
10/759692 |
Filed: |
January 16, 2004 |
Current U.S.
Class: |
148/281 ;
420/425 |
Current CPC
Class: |
C22C 27/02 20130101;
C23C 8/10 20130101 |
Class at
Publication: |
148/281 ;
420/425 |
International
Class: |
C22C 027/02; C23C
008/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2003 |
DE |
103 04 756.5 |
Claims
1. (Original) A niobium wire that it is enriched with oxygen.
2. (Original) A niobium wire in accordance with claim 1, wherein
the oxygen is in a concentration of about 3,000 to 30,000
.mu.g/g.
3. (Original) A process for producing oxygen-enriched niobium wire,
comprising the steps of: treating niobium in an oxygen-containing
atmosphere in a closed chamber at elevated temperature; and drawing
the niobium treated in this way into wire.
4. (Original) A process in accordance with claim 3, wherein the
treating step is carried out in an atmosphere of air.
5. (Original) A process in accordance with claim 3, wherein the
drawing step includes drawing the niobium into wire having a
diameter of 0.2-0.4 mm.
6. (Original) A process in accordance with claim 3, wherein the
treating step is carried out at temperatures of 600-800.degree.
C.
7. (Original) A process in accordance with claim 3, wherein the
treating step is carried out at pressures below 5 mbars.
8. (Original) A process in accordance with claim 3, wherein the
drawing step is carried out at room temperature.
9. (Original) Use of oxygen-enriched niobium wire for connection to
niobium or niobium oxide capacitors.
Description
BACKGROUND OF THE INVENTION
[0001] The invention concerns a novel niobium wire, a process for
producing it, and its use for connection to niobium or niobium
oxide capacitors.
[0002] Wires made of refractory metals are used for the electrical
connection of metal powder capacitors. Tantalum wires are generally
used for this purpose. This has the disadvantage of a relatively
high sintering temperature. As a result, the surface of the powder
anode cannot be completely used, because the powder partially
sinters together. Furthermore, the use of tantalum wires with
niobium and niobium oxide capacitors results in non-recyclable
waste. Moreover, the price of tantalum is subject to considerable
speculation, so that the costs for the raw material are difficult
to calculate and control.
[0003] Niobium wires have already been recommended for the
connection of powder anodes. For example, U.S. Pat. No. 6,358,625
B1 describes anode wires made of niobium or tantalum, which, to
improve adhesion, are treated with oxygen in such a way that
surface enrichment on the order of 35 atom % in a thickness of
about 50 nm is obtained. Niobium and tantalum wires normally
contain only small amounts of oxygen. Oxygen concentrations of
50-300 .mu.g/g are specified for tantalum. The surface enrichment
does not affect the general properties, such as conductivity, but
increases adhesion. Sintering temperatures around 1,250.degree. C.
are specified.
SUMMARY AND DESCRIPTION OF THE INVENTION
[0004] The object of the present invention is to provide thermally
stable niobium wires in the range of 1,200 to 1,400.degree. C.
[0005] This object is achieved by niobium wire that is highly
enriched with oxygen. The oxygen concentration is preferably about
3,000 to 30,000 .mu.g/g. The wires are suitable for connection
especially to niobium or niobium oxide capacitors.
[0006] It is assumed that the interstitial impurities reduce the
lattice mobility and block the grain boundaries in such a way that
coarse grain development at the sintering temperature of the powder
anodes is reduced.
[0007] The production process involves loading the niobium with
oxygen by diffusion processes at elevated temperatures of
preferably 600 to about 800.degree. C. and pressures below 5 mbars.
This is usually done in an oxygen-containing atmosphere, e.g., in
pure oxygen or oxygen-containing gas mixtures, such as air. This
yields a temperature-stabilized niobium alloy, which at
1,200-1,400.degree. C. has no appreciable vapor pressure of metals
that can have a negative effect on the stability (dielectric) of
the Nb.sub.2O.sub.5 layer by being deposited on the anode bodies.
The alloy can be worked at room temperature into wire 0.2-0.4 mm in
diameter.
[0008] The wires are preferably used as lead wires in niobium or
niobium oxide capacitors. Capacitors of this type are produced from
metallic niobium powder in the same way that tantalum capacitors
are produced. After sintering (together with the wire), the
metallic niobium is "formed," i.e., anodically oxidized, on the
surface to form an extremely thin dielectric Nb.sub.2O.sub.5
layer.
[0009] The following example explains the invention in greater
detail without limiting it.
EXAMPLE
[0010] Niobium in the form of prewire is loaded with oxygen at
temperatures of 600-800.degree. C. and pressures below 5 mbars in
such a way that, as a result of the simultaneously occurring
diffusion processes, oxygen enrichment occurs with respect to the
(wire) bulk. This results in a niobium alloy with oxygen
concentrations of 3,000 to 30,000 .mu.g/g. The niobium alloy
produced in this way is drawn into wires 0.2-0.4 mm in diameter at
room temperature.
[0011] While the oxygen-enriched niobium wire has been described in
conjunction with specific embodiments, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art in light of the disclosure herein. It is
intended that the meets and bounds of the invention be determined
by the appended claims rather than by the language of the above
specification, and that all such alternatives, modifications and
variations which form a function or co-jointly or cooperative
equivalent are intended to be included within the spirit and scope
of these claims.
* * * * *